Commentary on: “White Matter Damage of the Brain is Associated With Poor Outcomes in Vascular Surgery Patients with Claudication: A Pilot Study”

Abstract

Changes in cerebral white matter can be investigated using newer MRI-diffusion technologies. In the current issue of the European Journal of Vascular and Endovascular Surgery, a pilot study reports on the association between peripheral arterial disease (PAD) and white matter changes in the brain using MRI-diffusion imaging and calculation of fractional anisotropy. The study reports a reduction in the fractional anisotropy scale in patients with PAD, especially those suffering fatal or severe cardiovascular events during follow up. This is a new finding, which is worthy of further evaluation. In particular, such complex measurements need to be validated regarding inter-individual and inter-observer variability: is the anisotropy value the same in the morning as in the evening? Water diffusion displays directionality because of the presence of complex microstructural barriers in tissue. The extent of directionality of water diffusion can be expressed as fractional anisotropy, but what does this actually mean, and how is it calculated? It has been speculated to reflect fiber density, axonal diameter, myelination in white matter and metabolism. The current pilot study showing this new association is small, and its results must, therefore, be validated in larger prospective studies (as was stated by the authors). However, a study like this actually raises more questions than it answers: How does fractional anisotropy develop differently in patients with PAD compared to the changes observed in an ageing human? Are the white matter changes in aorto-iliac atherosclerosis different from